EFFECT OF LIMITED WATER SUPPLY ON ROOT GROWTH AND DEVELOPMENT OF WINTER WHEAT AND THE CHARACTERS OF SOIL MOISTURE USE BEFORE PLANTING

Experiments were conducted in the man-cont rolled water supply field at the Gucheng Agrometeorological Experimental Base of the Chinese Academy of Meteorological Sciences.Under the condition of sufficient soil moisture before planting, water was supplied for winter wheat with three scheme :I₁, 75 mm supplied water at jointing stage; I₂, 37.5 mm supplied water at returning-green stage and 37.5 mm at jointing stage; I_CK, no water supply during whole growth season.The precipitation during the grow th season was kept out.Results indicated that under I₁, the sufficient soil moisture before planting and limited water stress reduce the winter wheat root weight in the upper soil layer, and allocate more dry matter to the deeper root system.It contributes to the increase of the water use in deeper soil and the soil moisture use before planting.In addition, the water supply for winter wheat at jointing stage under I₁ helps increase the effective transpiration proportion at the key water dem and ing stage, and improves the water use efficiency.Although water stress decreases ears per m² in I₁, but the increase of grain numbers and grain weight contributes to the yield increase.